Embodiments of the present invention are directed generally to ultrasonic imaging. More particularly, various embodiments of the present invention are directed to apparatus and methods for generating 2D images from multiple 2D slices at different spatial locations.
Conventional 2D ultrasound scanners produce a two-dimensional slice by using a transducer to transmit ultrasonic pulses and receive echoes from structures inside a body. While the transducer is held in one position, pulses are fired to multiple points throughout a 2D scan area. The scan area is formed in a single plane and has a very thin thickness. The echo information is then displayed as a planar image made up of 2D pixels. The displayed information depends on specific properties of the transducer such as frequency, focal range, and axial and lateral resolution. While certain properties of the transducer can be varied (e.g., transmission frequency, receive frequency), it remains desirable to improve image quality by improving tissue contrast in conventional 2D images. Thus, there is a need for methods and apparatus of ultrasound imaging that continue to improve tissue contrast.
Two conventional methods of contrast enhancement concern filtering and utilizing a dynamic window. The filtering and windowing methods may decrease the amount of information in the image because of the presence of speckle. Thus, there is a need for methods and apparatus of ultrasound imaging that improve tissue contrast by reducing speckle.
In accordance with one embodiment of the present invention, a medical diagnostic ultrasound system for developing a 2D image having contrast enhancement comprises an ultrasonic transducer for receiving ultrasonic information from a volumetric region of a body, memory storing adjacent image lines or planes formed from received ultrasonic information from the volumetric region, a rendering box control module defining a thickness of a rendering box overlapping a portion of the adjacent image lines or planes, and a volume rendering processor for combining and projecting portions of image lines or planes within the rendering box onto a 2D image based on volume rendering techniques that enhance contrast.
The ultrasonic transducer may be a 3D transducer or a 2D matrix array. The system may further comprise a volume scan converter that generates the image lines or planes based on geometric information that calculates a position of neighboring ultrasonic information to derive voxel data. The volume rendering processor may project the portion of the image lines or planes in the rendering box in real-time. The system may further comprise memory for storing the ultrasonic information before being scan converted to form the image lines or planes. The volume rendering processor may employ algorithms for surface texture and maximum transparency. The volume rendering processor may perform at least one of the following operations upon the image lines or planes: surface texture, maximum transparency, transparent minimum, and gradient light rendering. The transducer may operate in at least one of the following acquisition modes: conventional grayscale sonography, 2D compound imaging, color Doppler, and duplex sonography with spectral Doppler. The transducer may receive tissue harmonic imaging information. The transducer may receive pulse inversion harmonic imaging information.
Certain embodiments of the present invention comprise a method for developing a 2D image representation for image contrast enhancement in a medical diagnostic ultrasound system comprising the steps of: receiving ultrasonic information from a volumetric region of a body, storing adjacent image lines or planes formed from received ultrasonic information from the volumetric region, forming a rendering box overlapping a portion of the adjacent image lines or planes and having a thickness, and volume rendering the rendering box for combining and projecting portions of image lines or planes within the rendering box onto a 2D image based on volume rendering techniques that enhance contrast.
The step of receiving ultrasonic information may be performed by a 3D transducer or a 2D matrix array. The method may further comprise a step of volume scan converting that generates the image lines or planes based on geometric information that calculates a position of neighboring ultrasonic information to derive voxel data. The step of volume rendering may project the portion of the image lines or planes in the rendering box in real-time. The method may further comprise a step of storing the ultrasonic information before being scan converted to form the image lines or planes. The step of volume rendering may perform at least one of the following operations upon the image lines or planes: surface texture, maximum transparency, transparent minimum, and gradient light rendering. The step of receiving ultrasonic information may employ at least one of the following acquisition modes: conventional grayscale sonography, 2D compound imaging, color Doppler, and duplex sonography with spectral Doppler. The step of receiving ultrasonic information may comprise receiving tissue harmonic imaging information. The step of receiving ultrasonic information may comprise receiving pulse inversion harmonic imaging information.